1. Field of the Invention
The invention relates to a wood planing machine, more particularly to a wood planing machine which is provided with a carriage locking mechanism for releasably locking a cutter carriage thereof.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional wood planing machine 10 according to U.S. Pat. No. 5,771,949 is shown to include a machine base 11, left and right pairs of upstanding posts 12, and a cutter carriage 13.
As illustrated, the machine base 11 has opposite mounting sides 111 spaced apart from each other in a transverse direction, and opposite feed-in and take-out sides spaced apart from each other in a longitudinal direction. The upstanding posts 12 (only one is shown in FIG. 2) extend upward from the machine base 11 at the mounting sides 111. The cutter carriage 13 is disposed above the machine base 11, and has opposite end portions 130 mounted movably on the upstanding posts 12 for sliding movement of the cutter carriage 13 along the upstanding posts 12. A cutter device 140 (see FIG. 3) is mounted on the cutter carriage 13, and is rotatable about a horizontal axis that extends in the transverse direction.
A pair of screw rods 15 (see FIG. 2) are mounted rotatably on, and extend upwardly from the machine base 11 at the mounting sides 111 to pass threadedly through the cutter carriage 13 at the opposite end portions 130 thereof. The screw rods 15 have lower ends coupled with the transmission rod 14 (see FIG. 3) via a gear assembly which are also disposed in the machine base 11. A turning handle 16 is provided at the top end of one of the screw rods 15 such that rotation of the latter will cause the cutter carriage 13 to slide along the upstanding posts 12 so as to define a gap between the cutter carriage 13 and the machine base 11 for passage of a work piece 17 to be processed.
As best illustrated in FIGS. 3,4 and 5, a carriage locking mechanism 20 includes a manually operable handle 21, two pairs of locking linkages 22 mounted respectively on two opposite ends of the handle 21, and four post clamps 23 anchored on the cutter carriage 40 and associated with the upstanding posts 12, respectively. Each of the locking linkages 22 includes first and second linkage members 221, 222 connected pivotally to each other at inner ends thereof and to the handle 21, and further connected pivotally to an adjacent pair of the post clamps 23 at outer ends thereof. Each of the second linkage members 222 is formed as two sliding pieces with a biasing spring 223 disposed therebetween. The handle 21 is movable against biasing action of the spring 223 from a releasing position (see FIG. 4) to a locking position (see FIG. 5), where an adjacent pair of the post clamps 23 are forced toward a respective one of the right and left pairs of the upstanding posts 12. At the locking position, the first and second linkage members 221, 222 are disposed in a straight line. Thus, the carriage 13 is locked relative the upstanding posts 12 so as to retain the same at a desired height relative to the machine base 11.
Some disadvantages that result from the use of the aforesaid conventional wood planing machine are as follows:
(i) It is noted that the carriage locking mechanism 20 employed in the conventional wood planing machine 10 includes a relatively large number of components, thereby resulting in a relatively long assembly time. PA1 (ii) Fatigue of the springs 223 due to long tern use of the locking mechanism 20 will weaken the locking strength of the post clamps 23 relative to the upstanding posts 12.